The present invention relates to fuel and liquid level gauges, and more particularly to a gauge which measures the fuel or liquid level optically by means of a fiber optic element.
Gauges for fuel and liquid tank levels are employed, for example, in vehicles. The most common type of fuel gauge that is used at present is an electro-mechanical gauge. A float element which stays on the fuel surface changes the position of a contact on a resistance wire as the fuel level changes. This is read out electrically and displayed on the vehicle dashboard. Such gauges are inaccurate and wear out with time because they have moving parts. The inaccuracies are aggravated by fuel tanks which have convoluted configurations.
U.S. Pat. No. 3,995,168 describes an electro optical fluid measurement system for display of the level and specific density of a liquid contained within a tank. The system employs a group of fiber optic bundles supported within a tank at a multiplicity of locations from the top to the bottom of the tank. The level is detected by measuring light from the respective groups of bundles to determine which bundle location is exposed above the liquid level. To achieve a large number of possible liquid level positions a corresponding number of fiber optic bundles must be used, thereby increasing the complexity and expense of the system.
It is therefore an object of the present invention to provide an improved fuel or liquid level gauge which is reliable and accurate.
A further object of the invention is to provide a fuel or liquid gauge which has no moving parts.
Yet another object is to provide a fuel or liquid level gauge which measures the liquid level optically.